Dtc P0504 Brake Switch A / B Correlation
DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE VOLTAGE)
INSPECT STOP LIGHT SWITCH ASSEMBLY
INSPECT ECM (STP AND ST1 - VOLTAGE)
DTC P0504 Brake Switch "A" / "B" Correlation |
DESCRIPTION
The stop light switch is a duplex system that transmits two signals: STP and ST1-. These two signals are used by the ECM to monitor whether or not the brake system is working properly. If the signals, which indicate the brake pedal is being depressed and released, are detected simultaneously, the ECM interprets this as a malfunction in the stop light switch and stores the DTC.- HINT:
- The normal signal conditions are as shown in the table below.
Signal (ECM Terminal)
| Brake Pedal Released
| In Transition
| Brake Pedal Depressed
|
STP
| OFF
| ON
| ON
|
ST1-
| ON
| ON
| OFF
|
- [OFF] denotes ground potential.
- [ON] denotes battery potential (+B).
- On the Techstream, both the Data List items Stop Light Switch and ST1 are ON when the brake pedal is depressed because the ST1 indication characteristic is opposite to the Stop Light Switch indication.
DTC No.
| DTC Detection Condition
| Trouble Area
|
P0504
| Conditions (a), (b) and (c) continue for 0.5 seconds or more
(1 trip detection logic):
(a) Ignition switch ON
(b) Brake pedal released
(c) STP signal OFF when ST1- signal OFF
| - Open or short in stop light switch signal circuit
- Stop light switch assembly
- ECM
|
WIRING DIAGRAM
INSPECTION PROCEDURE
- NOTICE:
- Inspect the fuses for circuits related to this system before performing the following inspection procedure.
- HINT:
- Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
- Stop light switch conditions can be checked using the Techstream.
- Connect the Techstream to the DLC3.
- Turn the ignition switch to ON.
- Turn the Techstream on.
- Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light Switch and ST1.
- Check the Data List indication when the brake pedal is depressed and released.
Brake Pedal Operation
| Stop Light Switch
| ST1
|
Depressed
| ON
| ON
|
Released
| OFF
| OFF
|
| 1.INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE VOLTAGE) |
Disconnect the stop light switch assembly connector.
Turn the ignition switch to ON.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
Tester Connection
| Switch Condition
| Specified Condition
|
A65-2 - Body ground
| Always
| 11 to 14 V
|
A65-4 - Body ground
| Ignition switch ON
| 11 to 14 V
|
Text in Illustration*a
| Front view of wire harness connector
(to Stop Light Switch Assembly)
|
| | REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - BATTERY) |
|
|
| 2.INSPECT STOP LIGHT SWITCH ASSEMBLY |
Inspect the stop light switch assembly (YARIS_NCP93 RM000001Y5401QX.html).
| 3.INSPECT ECM (STP AND ST1 - VOLTAGE) |
Disconnect the ECM connector.
Text in Illustration*a
| Brake Pedal Depressed
|
*b
| Brake Pedal released
|
*c
| Front view of wire harness connector
(to ECM)
|
Turn the ignition switch to ON.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
Tester Connection
| Brake Pedal Operation
| Specified Condition
|
A72-10 (ST1-) - Body ground
| Released
| 11 to 14 V
|
Depressed
| Below 1.5 V
|
A72-9 (STP) - Body ground
| Released
| Below 1.5 V
|
Depressed
| 11 to 14 V
|
| | REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - ECM) |
|
|
